Pesticides, Petrochemicals and Other Organic Chemicals in Drinking Water

Organic chemicals are a group of human-made chemical compounds that have been made for a variety of products—such as pesticides, gasoline, dry cleaning solvents, and degreasing agents. This group of chemicals includes volatile organic chemicals (VOCs), which are substances that contain carbon and evaporate or “off-gas” at room temperature, and synthetic organic chemicals (SOCs). VOCs and SOCs do not occur naturally in drinking water. When products made with VOCs and SOCs are improperly stored or disposed of, or when a spill occurs, they can contaminate groundwater and drinking water supplies.

What are examples of organic chemicals?

Examples of VOCs

  • Tetrachloroethylene (PCE) - PCE is a solvent used in the textile industry and as a component of aerosol dry-cleaning products. It can enter water systems through discharges from factories and dry-cleaning facilities. The current MCL* for PCE is 5 ppb. Vermont has an action level* (VAL) of 1 ppb for PCE in drinking water.
  • Trichloroethylene (TCE) - TCE is a solvent that is primarily used to remove grease from fabricated metal parts and is also used in the production of some textiles. The current MCL* for TCE is 5 ppb and a VAL* of 0.5 ppb for TCE in drinking water.

Examples of SOCs

  • Atrazine - Atrazine is an herbicide that is widely used as a weed killer, applied in agriculture with the greatest use on corn. Although its uses were greatly restricted in 1993, it can still be in the environment. The maximum contaminant level* (MCL) for atrazine is 3 ppb (parts per billion).
  • Di (2- ethylhexyl) phthalate (DEHP) - DEHP is the most commonly used of a group of related chemicals called phthalates or phthalic acid esters. The greatest use of DEHP is as a plasticizer (softener) for polyvinylchloride (PVC) and other polymers including rubber, cellulose and styrene. Several packaging materials and tubings used in the production of foods and beverages are PVC-contaminated with phthalic acid esters, primarily DEHP. The current MCL* for DEHP in drinking water is 6 ppb.

*Primary Maximum Contaminant Levels (MCLs) are legally enforceable standards determined by the Environmental Protection Agency to regulate public water systems. Each value represents the highest level of a chemical that is allowed in a public drinking water supply. Vermont Action Levels (VALs) are numeric guidelines researched and derived by the Health Department for a small number of chemicals that have MCLs but are of specific public health concern.

Health Concerns: Are organic chemicals harmful to my health?

Most health effects result when people drink water contaminated with organic chemicals over a long period of time.

Drinking water that contains VOCs can increase your risk for a variety of health problems. Some VOCs have been proven to cause cancer after prolonged exposure, while others are considered possible cancer risks. Consuming drinking water with high levels of PCE or TCE over many years may increase the risk for liver problems and cancer.

People who drink water that contains high levels of atrazine over many years may be at greater risk for cardiovascular problems and reproductive difficulties.

Some people who drink water containing DEHP more than the MCL over many years may be at greater risk for liver problems, reproductive difficulties and cancer.

Source: How do organic chemicals get into my water?

These chemicals get into drinking water from human activities. Examples include:

  • Pesticides sprayed too close to a well or other water supply
  • Accidental chemical spill
  • Improper disposal of chemicals down storm drains, household drains, or down the toilet
  • From old manufacturing sites where chemicals were improperly disposed

There are certain factors that could make your water contaminated with organic chemicals:

  • Distance between the well and a source of contamination – many wells contaminated with organic chemicals are located near industrial or commercial areas, gas stations, landfills, railroad tracks or farm fields.
  • Depth of your well – shallow wells are more likely to be affected than deep wells when contaminants have been spilled or applied on surface soils.
  • Local geology – groundwater covered by thin, porous soil or sand layers is most vulnerable, while dense, thickly layered soils may slow down the movement of contaminants and may help to absorb them.

If you suspect that your private drinking water is contaminated by organic chemicals, stop drinking the water and call the Health Department at 802-863-7220 or 800-439-8550 (toll free in Vermont).

Although many organic chemicals found in drinking water are due to contamination, others may be formed when drinking water is treated with chlorine to disinfect it. The chlorine reacts with organic materials found in water and forms certain VOCs known as disinfection byproducts. Learn more about disinfection byproducts

The Vermont Department of Environmental Conservation regulates VOCs in public water systems.

Testing: How do I know if organic chemicals are in my water?

You should test your private well water for VOCs and petroleum products if the water has the taste or smell of gasoline or solvents or an oily sheen to the water. You should also consider testing your water if the well is within 500 to 1,000 feet of a former or existing gasoline service station, or other fuel tanks.

To test drinking water for VOCs, the Health Department Laboratory offers Kit OA.

To test drinking water for semi-volatile chemicals and pesticides, the Health Department Laboratory offers Kit OL.

Order a test kit for organic chemicals

Treatment Options: Can I remove or lower the levels of organic chemicals in my water?

There are two ways to remove organic chemicals from drinking water: activated carbon/charcoal and reverse osmosis.

Activated Carbon/Charcoal
Water passes through an activated carbon filter. The organic chemicals bond to active sites in the carbon passages and are removed from the water. Over time, the active sites fill up and the filter is no longer effective. If the filter continues to be used at this point, the organic chemicals may be released back into the filtered water. Be sure to follow the maintenance schedule recommended by the manufacturer because disease-causing bacteria can build up in the filter. Install a carbon filtration system with an NSF/ANSI Standard 53 Certification. Search for an NSF/ANSI-certified carbon filtration system

Reverse Osmosis
A thin membrane allows pressurized water to pass through while holding back any pollutants to be drained off. This process uses three to 10 gallons of untreated water to make one gallon of drinking water. Reverse osmosis can remove many organic compounds but not all chlorination byproducts. Install a system with a National Sanitation Foundation (NSF/ANSI) Standard 58 Certification. Search for an NSF/ANSI-certified reverse osmosis treatment system

Chlorine can damage some reverse osmosis membranes, so pretreatment may be needed. Reducing the amount of chlorine added to your water, or using an activated carbon filter, can sometimes reduce organic compounds formed during chlorination. If the organic chemicals are not caused by chlorination, it’s important to find the source. Additional testing may be needed to determine the level of contamination.

Financial Assistance: Is there funding available to help me pay for my water system or treatment?

Vermont Wastewater and Potable Water Revolving Loan Fund
This program, also known as the On-site Loan Program, is available to certain Vermont residents for the repair or replacement of failed water supply and on-site wastewater systems. The On-site Loan Program is funded and administered by the Agency of Natural Resources, Department of Environmental Conservation with loan underwriting and servicing provided by the Opportunities Credit Union in Winooski. Your drinking water supply has to be a failed system and you must be living in the residence on a year-round basis to be eligible. The family income cannot exceed 200% of the state median household income. For more information about eligibility and how to apply, call 802-461-6051 or visit the website.

The NeighborWorks Alliance of Vermont
The NeighborWorks Alliance is made up of five local organizations offering full affordable housing services for income-eligible individuals. You may qualify for help from this program if you need money to install a water treatment system, drill a well, or repair or replace your septic system. For more information on eligibility, contact the local NeighborWorks HomeOwnership Center in your region.

Single Family Housing Repair Loans and Grants
This program offers loans and grants to exiting homeowners for well construction, repair and sealing. It's administered by the Rural Development office of the U.S. Department of Agriculture. The program is for low-income families who live in a rural area or a community with a population of 25,000 or less. The family income cannot exceed 50% of the median county income. Individuals who are 62 years of age or older may qualify for a grant or a combination of a loan and grant. Younger applicants are eligible only for loans.

Burlington, South Burlington, Essex Junction, Winooski and parts of Colchester are ineligible for the program. Even if your property is in an eligible area, your eligibility is still subject to income limits. For more information or to find out if your property is in an eligible area, call 802-828-6022 or visit the website.